There is a continuing need for improved security seals that are economical to manufacture, that are easy to use, and that provide effective security. A number of seals are known which are formed of molded plastic, comprising a hollow body having internal flexible fingers, to receive a shouldered stud, inserted into one end of the housing, in locking engagement. One of the disadvantages of such seals is the fact that to mold the seal of a single piece of plastic, the other end of the housing must be open to allow retracting of the core pin forming the housing opening and the flexible fingers. If this end of the housing is left open when the seal is used, it is possible to open the seal by inserting a suitable tool into the open end to disengage the fingers from the shoulder of the stud.
Various means have been used to close the housing. In U.S. Pat. No. 3,466,077 issued Sept. 9, 1969 to S. M. Moberg and assigned to the same assignee as the present application, there is illustrated a seal in which the end of the housing is formed into a close dome by heated dies. Although the seal disclosed therein has achieved considerable commercial success, the somewhat complicated machinery required for the closing of the end of the housing reduces the production rate, with corresponding increase in cost. Also, such closing machinery is not readily adaptable to seals of other configurations, and new closing machinery would have to be build for each type of seal.